Minimally-invasive tissue ablation using high contrast electric fields

Abstract

Described embodiments include a system and a method. A system includes an electromagnetic structure having a surface and a radiofrequency electromagnetic field source. The field source includes electronically controllable, artificially structured electromagnetic unit cells configured to create quasi-static electromagnetic fields within the electromagnetic structure. Each unit cell is responsive to a control signal. A selector circuit selects a quasi-static electromagnetic field pattern creating a high contrast electric field in a subwavelength electromagnetic cavity and is defined by the surface of the electromagnetic structure and an exterior surface of a perturbing object. The high contrast electric field has a power density that is localized to a volume adjoining the exterior surface of the perturbing object. A field pattern implementation circuit generates the control signal assigning electromagnetic field characteristic to each of the electromagnetic unit cells. The assigned radiofrequency electromagnetic field characteristics collectively creating the selected quasi-static electromagnetic field pattern.

Description

[0001]If an Application Data Sheet (ADS) has been filed on the filing date of this application, it is incorporated by reference herein. Any applications claimed on the ADS for priority under 35 U.S.C. §§ 119, 120, 121, or 365(c), and any and all parent, grandparent, great-grandparent, etc. applications of such applications, are also incorporated by reference, including any priority claims made in those applications and any material incorporated by reference, to the extent such subject matter is not inconsistent herewith.CROSS-REFERENCE TO RELATED APPLICATIONS[0002]The present application claims the benefit of the earliest available effective filing date(s) from the following listed application(s) (the “Priority Applications”), if any, listed below (e.g., claims earliest available priority dates for other than provisional patent applications or claims benefits under 35 USC § 119(e) for provisional patent applications, for any and all parent, grandparent, great-grandparent, etc. appli...

AI Technical Summary

Benefits of technology

The patent describes a system and method for creating a high contrast radiofrequency electric field in a subwavelength electromagnetic cavity. This is achieved by assigning a respective radiofrequency electromagnetic field characteristic to each of at least two electronically controllable, artificially structured electromagnetic unit cells associated with the surface of an electromagnetic structure. The system includes means for selecting the quasi-static electromagnetic field pattern, assigning the respective radiofrequency electromagnetic field characteristic, and implementing the assigned characteristic in each of the at least two unit cells. The high contrast radiofrequency electric field has been found to have a beneficial effect on target tissue in a living vertebrate subject, such as inducing cell death or inhibiting cell growth. The system and method can be used in various applications such as treating tumors or inhibiting the growth of scar tissue.

Problems solved by technology

However, it attenuates monotonically as it propagates, making it difficult to deliver substantial amounts of power to a localized spot deep within the body (e.g. at depth 5-50 cm) without exceeding the damage thresholds elsewhere.

However, the extremely long wavelength of electromagnetic radiation at those frequencies makes it difficult to achieve any substantial localization and concentration of electromagnetic energy density at a finite depth.

Ultimately, this is the reason why quasistatic electric fields cannot be fully localized with respect to all three dimensions.

While many eigenmodes, in particular of dipolar symmetry, can be excited to some extent by plane waves or quasi-uniform fields, the efficiency of their excitation is typically small.

Inefficient coupling leads to poor field localization and poor contrast in the power density, which is an obstacle in using that excitation scheme for tissue-sparing minimally-invasive RF ablation focused at a deep site in the tissue.

Furthermore, terms like “responsive to,”“related to,” or other past-tense adjectives are generally not intended to exclude such variants, unless context dictates otherwise.

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